Lipid Domain Pixelation Patterns Imposed by E-beam Fabricated Substrates

Ogunyankin, Maria O.; Torres, Andrea; Yaghmaie, Frank; Longo, Marjorie L.

doi:10.1021/la3008415

Cited by 17 publications

(31 citation statements)

References 30 publications

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“…The out-of-plane curvature of each bump was 9.7±0.8 μm −1 as measured previously by atomic force microscopy. 19 This is well above the curvature threshold range necessary for sorting the stiffer L o phase lipid from softer L d phase lipid.12 Note that each pattern was imprinted multiple times into a PMMA-coated silicon wafer (Fig. S1) allowing for statistical analysis.…”

Section: Resultsmentioning

confidence: 99%

“…In comparison, without walls, we showed in previous work that the initial L o area fraction supported by the same curvature lattice was significantly less, 0.43 ± 0.01. 19 …”

Section: Resultsmentioning

confidence: 99%

“…The lattice spacing controls the domain pixel size 19 and therefore, this substrate creates a gradient in line energy with the smallest line energy associated with the largest lattice spacing. On one end of the substrate the lattice spacing was 75 nm, while in the middle section it was 200 nm, and on the other end it was 400 nm as shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

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Compositional sorting dynamics in coexisting lipid bilayer phases with variations in underlying e-beam formed curvature pattern

Ogunyankin

Longo

2013

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Nanometer-scale curvature patterns of an underlying substrate are imposed on lipid multibilayers with each pattern imparting distinctly different sorting dynamics to a metastable pixilation pattern of coexisting liquid ordered (Lo) – liquid disordered (Ld) lipid phases. Therefore, this work provides pathways toward mechanical energy-based separations for analysis of biomembrane-associate species. The central design concept of the patterned sections of the silica substrate is a square lattice pattern of 100 nm projected radius poly(methyl methacrylate) (PMMA) hemispherical features formed by electron beam lithography which pixelates the coexisting phases in order to balance membrane bending and line energy. In one variation, we surround this pattern with three PMMA walls/fences 100 nm in height which substantially slows the loss of the high line energy pixelated Lo phase by altering the balance of two competing mechanism (Ostwald ripening vs. vesiculation). In another walled variation, we form a gradient of the spacing of the 100 nm features which forces partitioning of the Lo phase toward the end of the gradient with the most open (400 nm spacing) lattice pattern where a single vesicle could grow from the Lo phase. We show that two other variations distinctly impact the dynamics, demonstrating locally slowed loss of the high line energy pixelated Lo phase and spontaneous switching of the pixel location on the unit cell, respectively. Moreover, we show that the pixilation patterns can be regenerated and sharpened by a heating and cooling cycle. We argue that localized variations in the underlying curvature pattern have rather complex consequences because of the coupling and/or competition of dynamic processes to optimize mechanical energy such as lipid diffusion, vesiculation and growth, and phase/compositional partitioning.

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Section: Resultsmentioning

confidence: 99%

“…In comparison, without walls, we showed in previous work that the initial L o area fraction supported by the same curvature lattice was significantly less, 0.43 ± 0.01. 19 …”

Section: Resultsmentioning

confidence: 99%

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Compositional sorting dynamics in coexisting lipid bilayer phases with variations in underlying e-beam formed curvature pattern

Ogunyankin

Longo

2013

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“…64 We showed that nanometer-scale lipid sorting patterns are possible using an underlying substrate containing a square lattice pattern of hemispherical features, formed by standard e-beam lithography of a poly(methyl methacrylate) (PMMA) layer on silica. 65 The high-bending modulus (~6×10 -19 J) 66 A variety of methods have been developed to attach functional molecules to lipid headgroups. These include covalent bonding 68 and linkers such as single-stranded DNA, 69 biotin, 70 and glycan-phosphatidyl inositol.…”

Section: Discussionmentioning

confidence: 99%

Towards understanding of Nipah virus attachment protein assembly and the role of protein affinity and crowding for membrane curvature events.

Stachowiak¹,

Hayden²,

Negrete³

et al. 2013

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Pathogenic viruses are a primary threat to our national security and to the health and economy of our world. Effective defense strategies to combat viral infection and spread require the development of understanding of the mechanisms that these pathogens use to invade the host cell. We present in this report results of our research into viral particle recognition and fusion to cell membranes and the role that protein affinity and confinement in lipid domains plays in membrane curvature in cellular fusion and fission events. Herein, we describe 1) the assembly of the G attachment protein of Nipah virus using point mutation studies to define its role in viral particle fusion to the cell membrane, 2) how lateral pressure of membrane bound proteins induce curvature in model membrane systems, and 3) the role of membrane curvature in the selective partitioning of molecular receptors and specific affinity of associated proteins.4

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“…4 In the case of SPBs, micropatterning techniques have been applied to generate arrayed patches of L o and L d phases in the model membranes. [11][12][13][14][15][16] For example, Yoon et al accumulated L o and L d phases on a silicon substrate by locally modulating the surface curvatures. L o and L d phases were enriched on the at and corrugated surfaces, respectively, due to the difference in bending energy.…”

Section: Introductionmentioning

confidence: 99%

Micropatterned model membrane with quantitatively controlled separation of lipid phases

Okada

Morigaki

2015

RSC Adv.

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The localization of lipids and proteins in microdomains (lipid rafts) is believed to play important functional roles in the biological membrane. Herein, we report on a micropatterned model membrane that mimics lipid rafts by quantitatively controlling the spatial distribution of lipid phases. We generated a composite membrane of polymeric and fluid lipid bilayers by lithographic polymerization of diacetylene phospholipid(1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine: DiynePC). The composite membrane comprised polymer free-region (R 0 ), partially polymerized region (R 1 ), and fully polymerized region (R 2 ). As a ternary mixture of saturated lipid, unsaturated lipid, and cholesterol was introduced into the voids between polymeric bilayers, liquid-ordered (L o ) and liquid-disordered (L d ) lipid phases were accumulated in R 0 and R 1 , respectively. Local enrichment of L d phase in R 1 (and L o phase in R 0 ) was enhanced with a heightened coverage of polymeric bilayer in R 1 , supporting the premise that polymeric bilayer domains are inducing the phase separation. The pattern geometry (the area fractions of R 0 and R 1 ) also affected the enrichment due to the balance of gross L o /L d area fractions. Therefore, we could control the local L o /L d ratios by modulating the pattern geometry and polymer coverage in R 1 .Micropatterned model membrane with quantitatively controlled distribution of L o /L d phases offers a new tool to study the functional roles of lipid rafts by enabling to separate membrane-bound molecules according to their affinities to L o and L d phases.

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Lipid Domain Pixelation Patterns Imposed by E-beam Fabricated Substrates

Cited by 17 publications

References 30 publications

Compositional sorting dynamics in coexisting lipid bilayer phases with variations in underlying e-beam formed curvature pattern

Compositional sorting dynamics in coexisting lipid bilayer phases with variations in underlying e-beam formed curvature pattern

Towards understanding of Nipah virus attachment protein assembly and the role of protein affinity and crowding for membrane curvature events.

Micropatterned model membrane with quantitatively controlled separation of lipid phases

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